In order to ensure that Veterans have access to high-quality, evidence-based mental health services in the primary care setting, the VA has invested greatly in the development, testing, and implementation of effective models for primary care - mental health integration (PC-MHI). More recently, the VA has been working toward a complete transformation of its primary care clinics into patient-centered medical homes with the implementation of the Patient Aligned Care Team (PACT) model, which mandates continuous, comprehensive, collaborative care for all of the Veteran's health care needs. While national evaluations of each initiative are ongoing, little is known about the interaction between of these two related but distinct initiatives. The proposed study will begin to fill this gap with an in-depth qualitative examination of current practices and perceptions of PC-MHI under PACT implementation. Our objectives are to 1) describe and contextualize current practices of primary care - mental health integration in primary care clinics transforming to the PACT model; 2) characterize the perspectives of providers and nurse care managers regarding current and potential barriers and facilitators to successful mental health integration under the PACT model; and 3) characterize the perspectives and concerns of national PC-MHI leadership regarding mental health integration under the PACT model. To achieve the first two objectives we are proposing a rapid ethnography conducted in primary care clinics in two VA Medical Centers, utilizing the qualitative methods of nonparticipant observation and semi- structured interviews during three week-long site visits. To achieve the third objective we will conduct semi- structured telephone interviews with members of VA national leadership who are charged with supporting and promoting the implementation and sustainment of PC-MHI across the VA. While the study is informed by organizational theory that conceptualizes primary care clinics and the larger health systems in which they are embedded as complex adaptive systems (characterized by non-linear relationships and unpredictable responses to change), we largely employ an inductive research design using grounded theory techniques. As is common in grounded theory approaches, analysis of our data will begin immediately and continue throughout the study in order to allow earlier findings to inform later phases of data collection. Our ethnographic methods will allow us to create two robust in-depth case studies of PC-MHI in primary care clinics undergoing the transformation to PACT. The proposed study would complement but not duplicate national evaluations of PC-MHI and PACT. In collaboration with stakeholders, we will use our findings to inform the research design of a larger multi-site study in which we will A) examine a wide range of barriers, facilitators, and best practices in clinics across multiple regions and B) develop implementation strategies to enhance the implementation and sustainment of PC-MHI under PACT.